1. Field of the Invention
This invention is in the field of transfer mechanisms for removing objects from the bottom of a stack of such objects stored in a first magazine and for loading and stacking such objects serially in a second magazine using the linear motion of an extractor and cam surfaces that project into the second magazine to stack such objects in the second magazine.
2. Description of the Prior Art
The development of integrated circuit (IC) chips, particularly medium and large scale IC chips, has created a need for improved manufacturing processes which lend themselves to automating the mounting of IC chips and their lead frames on substrates as part of the process of manufacturing compact electronic circuit packages which are also known as micropackages. The mounting of such a chip and its lead frame in a fixture, for testing the chip and its lead frame and to facilitate the mounting of such chips on substrates is know. However, in automating the process of manufacturing micropackages and since most micropackages require IC chips of several different types, it is desirable to assemble in a single holder, or magazine, the necessary number of fixtures holding appropriate types of IC chips used in manufacturing a given micropackage.
To automate this manufacturing step requires a mechanism to transfer a fixture from one magazine, a transferor magazine, into a second magazine, a transferee magazine. To simplify the mechanism, to insure its reliability, and to minimize the risk of damage to an IC chip and its lead frame, each such fixture is removed from the bottom of the stack of such fixtures in a transferor magazine and is loaded into and become, at least until the next fixture is loaded into the transferee magazine, the bottommost fixture in the stack of such fixtures in the transferee magazine.
The closest known relevant prior art is that which has been developed with respect to holders or magazines for film slides or transparencies; i.e., fixtures for holding segments of developed photographic film for use with a projector to project an enlarged image on a screen, for example. However, none of the prior art transfer mechanisms are capable of withdrawing the bottommost fixture of a first stack of such fixtures from a transferor magazine and bottom loading each such fixture into a stack of such fixtures in a transferee magazine.